Question

If u = 18, v = 12, s = 210, then find the value of tIf u = 20, t = 5, s = 110, then find the value of v. pls send with img

Answer 1

Case 1:-

$u=18\\v=12\\s=210$

Using the above data in the third equation of kinematics, we get

$2as=v^2-u^2\\420a=144-324\\420a=-180\\a=-\frac{18}{42} \\a=-\frac{3}{7}$

Now let us use the first equation of kinematics.

$v=u+at\\12=18+-\frac{3t}{7}\\-6=-\frac{3t}{7}\\\\t=14s$

Case 2:-

$u = 20\\ t = 5\\ s = 110$

Using the above data in the second equation of kinematics, we get

$s=ut+\frac{at^2}{2} \\110=100+\frac{25a}{2}\\20=25a\\a=0.8$

Now let us apply this in first equation of motion.

$v=u+at\\v=20+4\\v=24\frac{m}{s}$